Bats population soars in Coats Marsh

They fly in silence and prefer the dark so you might not notice them, but next time you visit Coats Marsh Regional Park you could be in the presence of bats.

Regional District of Nanaimo parks staff confirmed an increase in the number of recorded bats living on the 46-hectare property, which was donated by Clyde Coats to The Nature Trust of B.C. and is now co-owned and managed by the RDN with a focus on environmental protection.

Bats had been roosting in a cabin (a legacy of the Stump Farm), but in early 2019, RDN staff determined it unsafe and demolished it, said Yann Gagnon, RDN manager of Parks Services, Recreation and Parks. A hired biologist determined 14 Little brown Myotis or Yuma Myotis bats were living in the cabin. To make up for the bats’ lost home, staff erected a bat house.

The big surprise came later in the year, in June, when the RDN asked the Gabriola Community Bat Group to record the number of bats living in the house – to their surprise they counted 53.

GROWLS member Liz Ciocea coordinates the bat group’s activities. She had contacted the former resident of the cabin, to see if she would help count bats in the park and around Gabriola. About 10 people around the island help to do annual tabulations.

The counting process happens 10 minutes after sunset, “civil twilight,” Liz explained, when the bats head out to feed. Volunteers quietly watch the bat house and use a counter to record each bat as it flies out. “There was lots of guano under the bat house indicating lots of bats roosting there,” Liz said.

Yann said they will be ask the bat group to undertake long-term bat monitoring in the park.

Vanessa Craig, a biologist specializing in small mammal ecology – and RDN director for Area B – said bats are a “very important component of the ecosystem. They help keep insect populations in check.” All bats in Canada are insectivores and small Little brown Myotis and Yuma Myotis eat flying insects like mosquitoes – a single bat can eat 600 in one night – and roost in cracks and crevices in tree bark, trees, and rock.

Bats need roosting spots and foraging and drinking habitat near fresh water and forest or grassy areas. Bat houses attract maternity colonies, Vanessa said, and females will “return year after year to a good maternity site.”

Threats to bats include large tree removal, particularly dead and dying ones; changes to buildings used for roosting; removal or alteration of rocky areas or cliffs; pesticide use; modification of riparian habitats and habitat fragmentation.

Little Brown Myotis is listed as endangered on the federal Species at Risk Act due to the threat of White-nose Syndrome, a fungus that appears on bats’ noses, wings and tail membranes. “The fungus appears to prevent bats from hibernating properly so that they use up their fat reserves and starve to death,” Vanessa explained. The syndrome has not been discovered in B.C. yet, but is devastating eastern populations. One case was identified near Seattle in 2016.

No baseline exists for how many bats have taken up residence at Coats Marsh over time as a wildlife species inventory has not been completed by the RDN, though the 2011-21 management plan for the park notes one “should be completed to assist in wildlife monitoring and protection efforts.”

Yann said they don’t intend to develop a new plan after the current one expires “as many of the park management recommendations from the initial management plan are still relevant and applicable.”

In her role as RDN director, Vanessa said the conversation about the park should be revisited. “Since this plan was developed, the discussion around parks on Gabriola has evolved and I think further discussions around some of those areas such as the extent to which we want to encourage or limit public access and circulation, and the focus of additional education and interpretation is necessary, and will help in setting the goals for the next phase.”

To support bats in and around Coats Marsh, the Gabriola bat group, which reports their observations to the conservation-focused BC Community Bat Program, would like to see more people on the island putting up bat houses and encourages anyone who sees bats to contact Liz (247-8805).

Oct. 24-31, GROWLS and the Gabriola bat group host Bat Week with several events at the library in Folklife Village. Vanessa Craig will do a presentation on bats Oct. 18 at 7 p.m. at the Roxy.